uint64_t metaslab_gang_bang = SPA_MAXBLOCKSIZE + 1; /* force gang blocks */
/*
+ * The in-core space map representation is more compact than its on-disk form.
+ * The zfs_condense_pct determines how much more compact the in-core
+ * space_map representation must be before we compact it on-disk.
+ * Values should be greater than or equal to 100.
+ */
+int zfs_condense_pct = 200;
+
+/*
* This value defines the number of allowed allocation failures per vdev.
* If a device reaches this threshold in a given txg then we consider skipping
* allocations on that device.
/*
* If the weights are identical, use the offset to force uniqueness.
*/
- if (m1->ms_map.sm_start < m2->ms_map.sm_start)
+ if (m1->ms_map->sm_start < m2->ms_map->sm_start)
return (-1);
- if (m1->ms_map.sm_start > m2->ms_map.sm_start)
+ if (m1->ms_map->sm_start > m2->ms_map->sm_start)
return (1);
ASSERT3P(m1, ==, m2);
* addition of new space; and for debugging, it ensures that we'd
* data fault on any attempt to use this metaslab before it's ready.
*/
- space_map_create(&msp->ms_map, start, size,
+ msp->ms_map = kmem_zalloc(sizeof (space_map_t), KM_PUSHPAGE);
+ space_map_create(msp->ms_map, start, size,
vd->vdev_ashift, &msp->ms_lock);
metaslab_group_add(mg, msp);
if (metaslab_debug && smo->smo_object != 0) {
mutex_enter(&msp->ms_lock);
- VERIFY(space_map_load(&msp->ms_map, mg->mg_class->mc_ops,
+ VERIFY(space_map_load(msp->ms_map, mg->mg_class->mc_ops,
SM_FREE, smo, spa_meta_objset(vd->vdev_spa)) == 0);
mutex_exit(&msp->ms_lock);
}
int t;
vdev_space_update(mg->mg_vd,
- -msp->ms_smo.smo_alloc, 0, -msp->ms_map.sm_size);
+ -msp->ms_smo.smo_alloc, 0, -msp->ms_map->sm_size);
metaslab_group_remove(mg, msp);
mutex_enter(&msp->ms_lock);
- space_map_unload(&msp->ms_map);
- space_map_destroy(&msp->ms_map);
+ space_map_unload(msp->ms_map);
+ space_map_destroy(msp->ms_map);
+ kmem_free(msp->ms_map, sizeof (*msp->ms_map));
for (t = 0; t < TXG_SIZE; t++) {
- space_map_destroy(&msp->ms_allocmap[t]);
- space_map_destroy(&msp->ms_freemap[t]);
+ space_map_destroy(msp->ms_allocmap[t]);
+ space_map_destroy(msp->ms_freemap[t]);
+ kmem_free(msp->ms_allocmap[t], sizeof (*msp->ms_allocmap[t]));
+ kmem_free(msp->ms_freemap[t], sizeof (*msp->ms_freemap[t]));
}
- for (t = 0; t < TXG_DEFER_SIZE; t++)
- space_map_destroy(&msp->ms_defermap[t]);
+ for (t = 0; t < TXG_DEFER_SIZE; t++) {
+ space_map_destroy(msp->ms_defermap[t]);
+ kmem_free(msp->ms_defermap[t], sizeof (*msp->ms_defermap[t]));
+ }
ASSERT0(msp->ms_deferspace);
metaslab_weight(metaslab_t *msp)
{
metaslab_group_t *mg = msp->ms_group;
- space_map_t *sm = &msp->ms_map;
+ space_map_t *sm = msp->ms_map;
space_map_obj_t *smo = &msp->ms_smo;
vdev_t *vd = mg->mg_vd;
uint64_t weight, space;
* Prefetch the next potential metaslabs
*/
for (msp = avl_first(t), m = 0; msp; msp = AVL_NEXT(t, msp), m++) {
- space_map_t *sm = &msp->ms_map;
+ space_map_t *sm = msp->ms_map;
space_map_obj_t *smo = &msp->ms_smo;
/* If we have reached our prefetch limit then we're done */
metaslab_activate(metaslab_t *msp, uint64_t activation_weight)
{
metaslab_group_t *mg = msp->ms_group;
- space_map_t *sm = &msp->ms_map;
+ space_map_t *sm = msp->ms_map;
space_map_ops_t *sm_ops = msp->ms_group->mg_class->mc_ops;
int t;
return (error);
}
for (t = 0; t < TXG_DEFER_SIZE; t++)
- space_map_walk(&msp->ms_defermap[t],
+ space_map_walk(msp->ms_defermap[t],
space_map_claim, sm);
}
* this metaslab again. In that case, it had better be empty,
* or we would be leaving space on the table.
*/
- ASSERT(size >= SPA_MINBLOCKSIZE || msp->ms_map.sm_space == 0);
+ ASSERT(size >= SPA_MINBLOCKSIZE || msp->ms_map->sm_space == 0);
metaslab_group_sort(msp->ms_group, msp, MIN(msp->ms_weight, size));
ASSERT((msp->ms_weight & METASLAB_ACTIVE_MASK) == 0);
}
/*
+ * Determine if the in-core space map representation can be condensed on-disk.
+ * We would like to use the following criteria to make our decision:
+ *
+ * 1. The size of the space map object should not dramatically increase as a
+ * result of writing out our in-core free map.
+ *
+ * 2. The minimal on-disk space map representation is zfs_condense_pct/100
+ * times the size than the in-core representation (i.e. zfs_condense_pct = 110
+ * and in-core = 1MB, minimal = 1.1.MB).
+ *
+ * Checking the first condition is tricky since we don't want to walk
+ * the entire AVL tree calculating the estimated on-disk size. Instead we
+ * use the size-ordered AVL tree in the space map and calculate the
+ * size required for the largest segment in our in-core free map. If the
+ * size required to represent that segment on disk is larger than the space
+ * map object then we avoid condensing this map.
+ *
+ * To determine the second criterion we use a best-case estimate and assume
+ * each segment can be represented on-disk as a single 64-bit entry. We refer
+ * to this best-case estimate as the space map's minimal form.
+ */
+static boolean_t
+metaslab_should_condense(metaslab_t *msp)
+{
+ space_map_t *sm = msp->ms_map;
+ space_map_obj_t *smo = &msp->ms_smo_syncing;
+ space_seg_t *ss;
+ uint64_t size, entries, segsz;
+
+ ASSERT(MUTEX_HELD(&msp->ms_lock));
+ ASSERT(sm->sm_loaded);
+
+ /*
+ * Use the sm_pp_root AVL tree, which is ordered by size, to obtain
+ * the largest segment in the in-core free map. If the tree is
+ * empty then we should condense the map.
+ */
+ ss = avl_last(sm->sm_pp_root);
+ if (ss == NULL)
+ return (B_TRUE);
+
+ /*
+ * Calculate the number of 64-bit entries this segment would
+ * require when written to disk. If this single segment would be
+ * larger on-disk than the entire current on-disk structure, then
+ * clearly condensing will increase the on-disk structure size.
+ */
+ size = (ss->ss_end - ss->ss_start) >> sm->sm_shift;
+ entries = size / (MIN(size, SM_RUN_MAX));
+ segsz = entries * sizeof (uint64_t);
+
+ return (segsz <= smo->smo_objsize &&
+ smo->smo_objsize >= (zfs_condense_pct *
+ sizeof (uint64_t) * avl_numnodes(&sm->sm_root)) / 100);
+}
+
+/*
+ * Condense the on-disk space map representation to its minimized form.
+ * The minimized form consists of a small number of allocations followed by
+ * the in-core free map.
+ */
+static void
+metaslab_condense(metaslab_t *msp, uint64_t txg, dmu_tx_t *tx)
+{
+ spa_t *spa = msp->ms_group->mg_vd->vdev_spa;
+ space_map_t *freemap = msp->ms_freemap[txg & TXG_MASK];
+ space_map_t condense_map;
+ space_map_t *sm = msp->ms_map;
+ objset_t *mos = spa_meta_objset(spa);
+ space_map_obj_t *smo = &msp->ms_smo_syncing;
+ int t;
+
+ ASSERT(MUTEX_HELD(&msp->ms_lock));
+ ASSERT3U(spa_sync_pass(spa), ==, 1);
+ ASSERT(sm->sm_loaded);
+
+ spa_dbgmsg(spa, "condensing: txg %llu, msp[%llu] %p, "
+ "smo size %llu, segments %lu", txg,
+ (msp->ms_map->sm_start / msp->ms_map->sm_size), msp,
+ smo->smo_objsize, avl_numnodes(&sm->sm_root));
+
+ /*
+ * Create an map that is a 100% allocated map. We remove segments
+ * that have been freed in this txg, any deferred frees that exist,
+ * and any allocation in the future. Removing segments should be
+ * a relatively inexpensive operation since we expect these maps to
+ * a small number of nodes.
+ */
+ space_map_create(&condense_map, sm->sm_start, sm->sm_size,
+ sm->sm_shift, sm->sm_lock);
+ space_map_add(&condense_map, condense_map.sm_start,
+ condense_map.sm_size);
+
+ /*
+ * Remove what's been freed in this txg from the condense_map.
+ * Since we're in sync_pass 1, we know that all the frees from
+ * this txg are in the freemap.
+ */
+ space_map_walk(freemap, space_map_remove, &condense_map);
+
+ for (t = 0; t < TXG_DEFER_SIZE; t++)
+ space_map_walk(msp->ms_defermap[t],
+ space_map_remove, &condense_map);
+
+ for (t = 1; t < TXG_CONCURRENT_STATES; t++)
+ space_map_walk(msp->ms_allocmap[(txg + t) & TXG_MASK],
+ space_map_remove, &condense_map);
+
+ /*
+ * We're about to drop the metaslab's lock thus allowing
+ * other consumers to change it's content. Set the
+ * space_map's sm_condensing flag to ensure that
+ * allocations on this metaslab do not occur while we're
+ * in the middle of committing it to disk. This is only critical
+ * for the ms_map as all other space_maps use per txg
+ * views of their content.
+ */
+ sm->sm_condensing = B_TRUE;
+
+ mutex_exit(&msp->ms_lock);
+ space_map_truncate(smo, mos, tx);
+ mutex_enter(&msp->ms_lock);
+
+ /*
+ * While we would ideally like to create a space_map representation
+ * that consists only of allocation records, doing so can be
+ * prohibitively expensive because the in-core free map can be
+ * large, and therefore computationally expensive to subtract
+ * from the condense_map. Instead we sync out two maps, a cheap
+ * allocation only map followed by the in-core free map. While not
+ * optimal, this is typically close to optimal, and much cheaper to
+ * compute.
+ */
+ space_map_sync(&condense_map, SM_ALLOC, smo, mos, tx);
+ space_map_vacate(&condense_map, NULL, NULL);
+ space_map_destroy(&condense_map);
+
+ space_map_sync(sm, SM_FREE, smo, mos, tx);
+ sm->sm_condensing = B_FALSE;
+
+ spa_dbgmsg(spa, "condensed: txg %llu, msp[%llu] %p, "
+ "smo size %llu", txg,
+ (msp->ms_map->sm_start / msp->ms_map->sm_size), msp,
+ smo->smo_objsize);
+}
+
+/*
* Write a metaslab to disk in the context of the specified transaction group.
*/
void
vdev_t *vd = msp->ms_group->mg_vd;
spa_t *spa = vd->vdev_spa;
objset_t *mos = spa_meta_objset(spa);
- space_map_t *allocmap = &msp->ms_allocmap[txg & TXG_MASK];
- space_map_t *freemap = &msp->ms_freemap[txg & TXG_MASK];
- space_map_t *freed_map = &msp->ms_freemap[TXG_CLEAN(txg) & TXG_MASK];
- space_map_t *sm = &msp->ms_map;
+ space_map_t *allocmap = msp->ms_allocmap[txg & TXG_MASK];
+ space_map_t **freemap = &msp->ms_freemap[txg & TXG_MASK];
+ space_map_t **freed_map = &msp->ms_freemap[TXG_CLEAN(txg) & TXG_MASK];
+ space_map_t *sm = msp->ms_map;
space_map_obj_t *smo = &msp->ms_smo_syncing;
dmu_buf_t *db;
dmu_tx_t *tx;
- int t;
ASSERT(!vd->vdev_ishole);
- if (allocmap->sm_space == 0 && freemap->sm_space == 0)
+ /*
+ * This metaslab has just been added so there's no work to do now.
+ */
+ if (*freemap == NULL) {
+ ASSERT3P(allocmap, ==, NULL);
+ return;
+ }
+
+ ASSERT3P(allocmap, !=, NULL);
+ ASSERT3P(*freemap, !=, NULL);
+ ASSERT3P(*freed_map, !=, NULL);
+
+ if (allocmap->sm_space == 0 && (*freemap)->sm_space == 0)
return;
/*
mutex_enter(&msp->ms_lock);
- space_map_walk(freemap, space_map_add, freed_map);
-
- if (sm->sm_loaded && spa_sync_pass(spa) == 1 && smo->smo_objsize >=
- 2 * sizeof (uint64_t) * avl_numnodes(&sm->sm_root)) {
- /*
- * The in-core space map representation is twice as compact
- * as the on-disk one, so it's time to condense the latter
- * by generating a pure allocmap from first principles.
- *
- * This metaslab is 100% allocated,
- * minus the content of the in-core map (sm),
- * minus what's been freed this txg (freed_map),
- * minus deferred frees (ms_defermap[]),
- * minus allocations from txgs in the future
- * (because they haven't been committed yet).
- */
- space_map_vacate(allocmap, NULL, NULL);
- space_map_vacate(freemap, NULL, NULL);
-
- space_map_add(allocmap, allocmap->sm_start, allocmap->sm_size);
-
- space_map_walk(sm, space_map_remove, allocmap);
- space_map_walk(freed_map, space_map_remove, allocmap);
-
- for (t = 0; t < TXG_DEFER_SIZE; t++)
- space_map_walk(&msp->ms_defermap[t],
- space_map_remove, allocmap);
+ if (sm->sm_loaded && spa_sync_pass(spa) == 1 &&
+ metaslab_should_condense(msp)) {
+ metaslab_condense(msp, txg, tx);
+ } else {
+ space_map_sync(allocmap, SM_ALLOC, smo, mos, tx);
+ space_map_sync(*freemap, SM_FREE, smo, mos, tx);
+ }
- for (t = 1; t < TXG_CONCURRENT_STATES; t++)
- space_map_walk(&msp->ms_allocmap[(txg + t) & TXG_MASK],
- space_map_remove, allocmap);
+ space_map_vacate(allocmap, NULL, NULL);
- mutex_exit(&msp->ms_lock);
- space_map_truncate(smo, mos, tx);
- mutex_enter(&msp->ms_lock);
+ /*
+ * For sync pass 1, we avoid walking the entire space map and
+ * instead will just swap the pointers for freemap and
+ * freed_map. We can safely do this since the freed_map is
+ * guaranteed to be empty on the initial pass.
+ */
+ if (spa_sync_pass(spa) == 1) {
+ ASSERT0((*freed_map)->sm_space);
+ ASSERT0(avl_numnodes(&(*freed_map)->sm_root));
+ space_map_swap(freemap, freed_map);
+ } else {
+ space_map_vacate(*freemap, space_map_add, *freed_map);
}
- space_map_sync(allocmap, SM_ALLOC, smo, mos, tx);
- space_map_sync(freemap, SM_FREE, smo, mos, tx);
+ ASSERT0(msp->ms_allocmap[txg & TXG_MASK]->sm_space);
+ ASSERT0(msp->ms_freemap[txg & TXG_MASK]->sm_space);
mutex_exit(&msp->ms_lock);
- VERIFY(0 == dmu_bonus_hold(mos, smo->smo_object, FTAG, &db));
+ VERIFY0(dmu_bonus_hold(mos, smo->smo_object, FTAG, &db));
dmu_buf_will_dirty(db, tx);
ASSERT3U(db->db_size, >=, sizeof (*smo));
bcopy(smo, db->db_data, sizeof (*smo));
{
space_map_obj_t *smo = &msp->ms_smo;
space_map_obj_t *smosync = &msp->ms_smo_syncing;
- space_map_t *sm = &msp->ms_map;
- space_map_t *freed_map = &msp->ms_freemap[TXG_CLEAN(txg) & TXG_MASK];
- space_map_t *defer_map = &msp->ms_defermap[txg % TXG_DEFER_SIZE];
+ space_map_t *sm = msp->ms_map;
+ space_map_t *freed_map = msp->ms_freemap[TXG_CLEAN(txg) & TXG_MASK];
+ space_map_t *defer_map = msp->ms_defermap[txg % TXG_DEFER_SIZE];
metaslab_group_t *mg = msp->ms_group;
vdev_t *vd = mg->mg_vd;
int64_t alloc_delta, defer_delta;
/*
* If this metaslab is just becoming available, initialize its
- * allocmaps and freemaps and add its capacity to the vdev.
+ * allocmaps, freemaps, and defermap and add its capacity to the vdev.
*/
- if (freed_map->sm_size == 0) {
+ if (freed_map == NULL) {
+ ASSERT(defer_map == NULL);
for (t = 0; t < TXG_SIZE; t++) {
- space_map_create(&msp->ms_allocmap[t], sm->sm_start,
+ msp->ms_allocmap[t] = kmem_zalloc(sizeof (space_map_t),
+ KM_PUSHPAGE);
+ space_map_create(msp->ms_allocmap[t], sm->sm_start,
sm->sm_size, sm->sm_shift, sm->sm_lock);
- space_map_create(&msp->ms_freemap[t], sm->sm_start,
+ msp->ms_freemap[t] = kmem_zalloc(sizeof (space_map_t),
+ KM_PUSHPAGE);
+ space_map_create(msp->ms_freemap[t], sm->sm_start,
sm->sm_size, sm->sm_shift, sm->sm_lock);
}
- for (t = 0; t < TXG_DEFER_SIZE; t++)
- space_map_create(&msp->ms_defermap[t], sm->sm_start,
+ for (t = 0; t < TXG_DEFER_SIZE; t++) {
+ msp->ms_defermap[t] = kmem_zalloc(sizeof (space_map_t),
+ KM_PUSHPAGE);
+ space_map_create(msp->ms_defermap[t], sm->sm_start,
sm->sm_size, sm->sm_shift, sm->sm_lock);
+ }
+
+ freed_map = msp->ms_freemap[TXG_CLEAN(txg) & TXG_MASK];
+ defer_map = msp->ms_defermap[txg % TXG_DEFER_SIZE];
vdev_space_update(vd, 0, 0, sm->sm_size);
}
vdev_space_update(vd, alloc_delta + defer_delta, defer_delta, 0);
- ASSERT(msp->ms_allocmap[txg & TXG_MASK].sm_space == 0);
- ASSERT(msp->ms_freemap[txg & TXG_MASK].sm_space == 0);
+ ASSERT(msp->ms_allocmap[txg & TXG_MASK]->sm_space == 0);
+ ASSERT(msp->ms_freemap[txg & TXG_MASK]->sm_space == 0);
/*
* If there's a space_map_load() in progress, wait for it to complete
int evictable = 1;
for (t = 1; t < TXG_CONCURRENT_STATES; t++)
- if (msp->ms_allocmap[(txg + t) & TXG_MASK].sm_space)
+ if (msp->ms_allocmap[(txg + t) & TXG_MASK]->sm_space)
evictable = 0;
if (evictable && !metaslab_debug)
for (m = 0; m < vd->vdev_ms_count; m++) {
metaslab_t *msp = vd->vdev_ms[m];
- if (msp->ms_map.sm_start > mg->mg_bonus_area)
+ if (msp->ms_map->sm_start > mg->mg_bonus_area)
break;
mutex_enter(&msp->ms_lock);
{
uint64_t ms_shift = msp->ms_group->mg_vd->vdev_ms_shift;
uint64_t offset = DVA_GET_OFFSET(dva) >> ms_shift;
- uint64_t start = msp->ms_map.sm_start >> ms_shift;
+ uint64_t start = msp->ms_map->sm_start >> ms_shift;
if (msp->ms_group->mg_vd->vdev_id != DVA_GET_VDEV(dva))
return (1ULL << 63);
mutex_enter(&msp->ms_lock);
/*
+ * If this metaslab is currently condensing then pick again as
+ * we can't manipulate this metaslab until it's committed
+ * to disk.
+ */
+ if (msp->ms_map->sm_condensing) {
+ mutex_exit(&msp->ms_lock);
+ continue;
+ }
+
+ /*
* Ensure that the metaslab we have selected is still
* capable of handling our request. It's possible that
* another thread may have changed the weight while we
continue;
}
- if ((offset = space_map_alloc(&msp->ms_map, asize)) != -1ULL)
+ if ((offset = space_map_alloc(msp->ms_map, asize)) != -1ULL)
break;
atomic_inc_64(&mg->mg_alloc_failures);
- metaslab_passivate(msp, space_map_maxsize(&msp->ms_map));
+ metaslab_passivate(msp, space_map_maxsize(msp->ms_map));
mutex_exit(&msp->ms_lock);
}
- if (msp->ms_allocmap[txg & TXG_MASK].sm_space == 0)
+ if (msp->ms_allocmap[txg & TXG_MASK]->sm_space == 0)
vdev_dirty(mg->mg_vd, VDD_METASLAB, msp, txg);
- space_map_add(&msp->ms_allocmap[txg & TXG_MASK], offset, asize);
+ space_map_add(msp->ms_allocmap[txg & TXG_MASK], offset, asize);
mutex_exit(&msp->ms_lock);
mutex_enter(&msp->ms_lock);
if (now) {
- space_map_remove(&msp->ms_allocmap[txg & TXG_MASK],
+ space_map_remove(msp->ms_allocmap[txg & TXG_MASK],
offset, size);
- space_map_free(&msp->ms_map, offset, size);
+ space_map_free(msp->ms_map, offset, size);
} else {
- if (msp->ms_freemap[txg & TXG_MASK].sm_space == 0)
+ if (msp->ms_freemap[txg & TXG_MASK]->sm_space == 0)
vdev_dirty(vd, VDD_METASLAB, msp, txg);
- space_map_add(&msp->ms_freemap[txg & TXG_MASK], offset, size);
+ space_map_add(msp->ms_freemap[txg & TXG_MASK], offset, size);
}
mutex_exit(&msp->ms_lock);
mutex_enter(&msp->ms_lock);
- if ((txg != 0 && spa_writeable(spa)) || !msp->ms_map.sm_loaded)
+ if ((txg != 0 && spa_writeable(spa)) || !msp->ms_map->sm_loaded)
error = metaslab_activate(msp, METASLAB_WEIGHT_SECONDARY);
- if (error == 0 && !space_map_contains(&msp->ms_map, offset, size))
+ if (error == 0 && !space_map_contains(msp->ms_map, offset, size))
error = ENOENT;
if (error || txg == 0) { /* txg == 0 indicates dry run */
return (error);
}
- space_map_claim(&msp->ms_map, offset, size);
+ space_map_claim(msp->ms_map, offset, size);
if (spa_writeable(spa)) { /* don't dirty if we're zdb(1M) */
- if (msp->ms_allocmap[txg & TXG_MASK].sm_space == 0)
+ if (msp->ms_allocmap[txg & TXG_MASK]->sm_space == 0)
vdev_dirty(vd, VDD_METASLAB, msp, txg);
- space_map_add(&msp->ms_allocmap[txg & TXG_MASK], offset, size);
+ space_map_add(msp->ms_allocmap[txg & TXG_MASK], offset, size);
}
mutex_exit(&msp->ms_lock);
git://git.camperquake.de / zfs.git / commitdiff